This invention relates to tubulars for sharply curved bore holes, holes whose radius of curvature is too small for running the usual steel tubular goods. Since lateral bore holes from inaccessible wells desirably have a straight section extending beyond the curved portion, a shaft entering this section needs to straighten easily. Desired characteristics of such a tubular shaft include the capability of unidirectional bending, resistance to twisting, compatibility with the usual well fluids, good burst and collapse pressure specifications and neutral buoyancy in a drilling fluid to avoid bore hole wall drag due to the earth's gravity. The ability to withstand high temperature is also desirable in situations where the tubular shaft is to be used to conduct high temperature fluids in secondary oil recovery operations.
My co-pending application Ser. No. 125,240, filed Feb. 27, 1980, entitled "Method and Apparatus for Forming Lateral Passageways" relates to the formation of lateral passageways from inaccessible wells and the instant invention is applicable thereto.